To each their own...If you feel safer treating water, then treat water. If not then dont. In my experience there are very few hard and fast rules when it comes to backpacking (LNT, food storage, etc. being the exceptions). Everyone has their own philosophy toward best practices. In my case I rarely treat water but here in the Southern Appalachian's there are more springs than you can shake a stick at so "good, clean" water is abundant. They key, like so many others have said, is source choice. Fresh mountain spring water is probably gonna be better than stinking cow pond water whether filtered, chemically treated, or nothing at all.